Float



P; DUNSHEAT'H FLOAT Filed Nov. 26,

Feb. 11, 1947.

Patented Feb. 11, 1947 FLOAT Percy Dunsheath, Abinger, England, assigner to W. T. Henleys Telegraph Works Company Limited, Wescott, Dorking, England, a British Company Application November 26, 1943, Serial N o. 511,849 In Great Britain November 28, 1942 8 Claims.

This invention relates to long ilexible floats for use in the manufacture of water-buoyant electric cable or for other purposes. In such cable the long flexible float generally forms a core about which are disposed one or more layers of wires constituting the cable conductor, which is usually provided with a flexible waterproof covering. For some purposes it is essential that the cable should possess a high resistance to compression in a lateral direction and yet be flexible lengthwise to permit a frequent reeling and unreeling without damage, These requirements necessitate a float that is rigid in a lateral direction but locally compressible in a longitudinal direction. By the present invention we provide a float meeting these requirements. It comprises a series of laterally rigid cellular elements with gaps between successive elements, each closed by a flexible band of waterproof material which overlaps the adjacent ends of the elements and makes water-tight joints therewith.

The invention will be more fully described with the aid of the accompanying drawing wherein- Figures 1, 2 and 3 are elevations of parts of examples of long flexible floats constructed in accordance with the invention, and

Figure 4 is an elevation of the stepped end of a buoyant electric cable embodying a float constructed according to the invention.

The examples of float shown in Figures 1 and 2 of the drawing each comprise a series of laterally rigid cellular elements I with gaps between successive elements. These cellular elements themselves may be of any material or materials that will result in their having adequate resistance to compression in a lateral direction. They may be closed, hollow containers which may be of metal, plywood or a tough plastic. One or both of the end walls 5 and 6 of each container may be of the same material as the circumferential wall I or of different material, and may or may not be flexible. Alternatively, the elements I may be of cellular material, for instance, cork or hard expanded rubber. The gaps between successive elements i are closed each by a exible band of waterproof material which overlaps the ends of the elements and makes water-tight joints therewith. In the example of float shown in Figure 1, the gap between the rst and second and second and third elements from the left are each closed by a separate band 8 applied as a convolute wrapping of tape of which the overlapping ends 9 and Iil make a tight joint with one another. The Width of the tape is of the same order as the length of the elements, so that its edges overlap the adjacent ends of the circumferential walls of the elements by a substantial amount. The gaps between the third and fourth and fourth and fifth elements from the left are closed by endless bands iI, each of which is stretched elastically and slipped into position. The normal circumferential lcngth of the endless band may be less than that of the cellular elements, so that it is under tension when in position and tightly grips the ends of the elements. In the example of float shown in Figure 2, the gaps between successive elements I are closed by a continuous helical wrapping I2 of tape of a width approximating to the length of an element, applied with substantial overlap, for instance, an overlap of one third of the width of the tape. The overlapping margins of the tape make joint with one another and the wrapping makes joint with the circumferential surfaces of the underlying elements.

The preferred material for the flexible bands is soft vulcanised rubber, but other materials that are similar as regards their relevant physical properties may be used as substitutes for rubber. Examples are neoprene (chloroprene), alkali polysulphides, viscose, The bands may be cemented to the underlying circumferential surfaces of the elements or, if the bands are to be of vulcanised material, for instance, vulcanised rubber, they may be applied in the unvulcanised state and vulcanised to such surfaces. When bands are used that are formed by applying a continuous helical wrapping to the assembled elements, it is preferable to use unvulcanised rubber tape and later to vulcanise lt to convert it into a continuous covering which is vulcanised to the elements where these are of an appropriate material, for instance, hard rubber, or brass.

In the example of construction shown in Figure 3 of the drawing, the cellular elements I are in the form of open ended containers comprising a circumferential wall 1 and a single end wall E. These containers are aligned with the open end of one near the closed end of the next as shown and the gaps between the circumferential walls of adjacent containers are bridged by ilexible bands 8, for instance, elastically stretched endless rubber bands. The open ends of each of these containers may be strengthened by forming a circumferentialiy extending groove I3 therein. This also helps to retain the `band in place on the container. The containers themselves may conveniently be of metal, for example, tin-plate, in which case the seam between the end wall 6 and circumferential wall 'I assists to retain the band 8 on the closed end of the container.

,covering In cases where no seam is present, there may be a groove similar to that at the open end of the container. To avoid damage to the bands the rim of each container may be bent inwardly as shown at I4.

In some cases the longitudinal tension to which the float may be subjected after its manufacture, for instance, during its incorporation in an electric cable or when in service, may render lit desirable to provide some additional coupling means between successive elements in order to remove or reduce the strain on the exible bands. In that event it is preferred, las is shown, for example, in Figure 2, to couple the ccntainersor other cellular elements to one another along the axis of the float by ilexible couplingmembers I which tend to hold them in spacedrelationship and to maintain them in alignment with one another -but permit the central parts of the containers to approach one another and take up positions with their axes inclined to one another.

Coupling members of this form are described in vcompared with a float of similar construction not fitted with flexible bands whilst the waterproof I6 remains sound. Should this become damaged, however, the'latter form of oat will become partially flooded and its buoyancy considerably reduced but the buoyancy of the improved form of float will not be affected by damage to the sheath i6 unless `it is accompanied -by damage to an element in the form of a closed hollow container or to a flexible band between two elements and then Aonly to the extent of one element.

Asr the volume of the enclosed spaces between the ,ends of successive cellular elements 1 may be reduced by a radially inward bending of the unsupported part of the bandi! or l2 due totension in the band or pressure exerted by themedium in which the float operates, the yenclosed spaces may be lled with gas under a super-atmospheric pressure suflicient wholly or in part to counteract these tendencies. This maybe effected by including in each enclosed space an appropriate quantity of a substance which will liberate gas when subjected to heat. Where this course is taken it is preferable to apply the bands to the element in an unvulcansed or partially vulcanised state and to cure them `by heat treating them within a mould which maintains the margins of the band in contact with the elements and serves to support ,the central part against the pressure of the ygas generated during theheat treatment. This mould may be a temporary mould or, in the caseor" a oat for use as a core of a buoyant cable, it may be constituted by the cable conductor stranded around it.

Where the float is to form the core of an electric cable it may be an advantage to use as the cellular elementscontainers made entirely of metal, for instance, vof tin-plate or sheet brass and to connect them together electrically, for instance, bythe usefof central ilexiblercouplng members of metal. In the example of cable shown in Figure 4, the core is built up of a series of closed metal canisters I connected end to end by central flexible coupling members l5 of metal strip to form an electrically continuous core. The spaces between successive Acontainers are closed by rubber bands 8 and theenclosure lled with gas under superatmospheric pressure. The

Acontainers themselves are also lilled with gas under a similar pressure or a higher pressure.

`Over the core the stranded conductor is applied in two layers I1 and I9 which are of opposite layfandseparated by a layer I8 of rub'ber-proofed fabric tape. A further layer 20 of similar tape is applied over the outer layer of wires and the whole enclosed in a sheath I6 of tough rubber or other flexible Waterproof material. In such a construction the float forms a continuous electrical conductor which may be connected in parallel with the main conductor which it supports, thusincreasing the conductivity of a cable or" 'a given overall diameter,.oralternatively permitting a reduction in size of fthe main conductor and hence in the weight and overall sizeof a cable of given conductivity.

What I claim as my invention is:

1. A long flexible float comprisinga seriesof laterally rigid cellular elements disposed with gaps between successive elements of said series and means enclosing each gap, said means comprising a flexible band of waterproof material overlapping the adjacent ends of the kelements defining the gap andmaking water-tight joints therewith.

2. A long kilexible 4float comprising a series of laterally rigid cellular elementswith gaps between successive elements'of Vsaidseries and means `enclosingthe gaps, said means comprising for each gap, a separate flexible band which overlaps the adjacent ends of the'elements dening'the gap and makes water-tight joints therewith.

3. A long iiexible iloat comprising a series of Ylaterally rigid cellular velements with Vgaps vbetween successiveelements of said series and means enclosing the gaps, said means comprising for each gap, a separate flexibleband in the form of a convolute wrapping which overlaps the adjacent ends of the elements defining the gap and makes water-'tight joints therewith and of which the overlapping ends are joined together.

4. A long flexible iloat comprising a series of laterally rigid cellular elements with gaps between successive elements of said series and means enclosing the gaps, said means comprising for each gap an elastically stretchable endless band which overlaps theadjacent ends of the elements defining the gap and makes water-tight joints therewith.

5. A long flexible oatcomprising a series of laterally rigid cellular Aelements with gaps between successive elements of said series andmeans enclosing said gaps comprising a continuoushelical wrapping lof a band of flexible waterproof material, applied tosaid elements and making joint with the circumferential l,surfaces thereof, onemarginoi' the band continuously overlapping Ythe other and making Vjoint therewith.

6. A long `exible float comprising aseries of laterally rigid cellular elements with gaps between successive elements ofthe series. and a Vcontinuous'flexible `covering .vulcanised to the ,ci-rcumferential surfaces of `,the elements.

7. A long @flexible .float comprising la series-of .mutually spaced open-,ended containers disposed with the open end of one container adjacent the closed end of the next and means enclosing each gap between successive elements, said means comprising a flexible band of waterproof material overlapping the adjacent ends of the elements defining the gap and making water-tight joints therewith.

8. A long exible float comprising a series of laterally rigid cellular elements separated by intervening buoyancy elements containing gas under super-atmospheric pressure, each of said intervening buoyancy elements being constituted by the contiguous end walls of two successive laterally rigid cellular elements and a circumferential wall formed by a flexible band of waterproof material which overlaps the adjacent ends of the two laterally rigid elements and makes joint therewith.

PERCY DUNSHEATH.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

